Add requester apis (#9)

* Fix react tests

* Add requester functions

* Add requester.

packages/core/src/__tests__/requester.test.ts

@@ -0,0 +1,42 @@
+import staat from '../staat';
+import { Staat } from '../types';
+
+type TestState = {
+  count: number;
+};
+
+const state: TestState = {
+  count: 37,
+};
+
+describe('requester', () => {
+  let sut: Staat<TestState>;
+  beforeEach(() => {
+    sut = staat(state);
+  });
+
+  it('selects from state', async () => {
+    let value: number = 10;
+    await sut.request(async ({ select }) => {
+      value = select(s => s.count);
+    });
+
+    expect(value).toBe(37);
+  });
+
+  it('reduces state', async () => {
+    await sut.request(async ({ reduce }) => {
+      reduce(s => ({ ...s, count: 99 }));
+    });
+
+    expect(sut.currentState.count).toBe(99);
+  });
+
+  it('accepts arguments', async () => {
+    await sut.request(async ({ reduce }, value: number) => {
+      reduce(s => ({ ...s, count: value }));
+    }, 489);
+
+    expect(sut.currentState.count).toBe(489);
+  });
+});

packages/core/src/__tests__/staat.test.ts

@@ -102,6 +102,7 @@ describe('staat', () => {
       expect(typeof sut.subscribe).toBe('function');
       expect(typeof sut.unsubscribe).toBe('function');
       expect(typeof sut.reduce).toBe('function');
+      expect(typeof sut.request).toBe('function');
     });
 
     it('reduces the value', () => {

packages/core/src/staat.ts

@@ -4,6 +4,7 @@ import {
   Staat,
   TransformerOrObject,
   LegacyStaat,
+  RequesterState,
 } from './types';
 import { isPromise, isTransformer } from './utils';
 
@@ -45,17 +46,39 @@ function makeReduce<TState>(container: StateContainer<TState>) {
   };
 }
 
+function makeSelect<TState>(
+  container: StateContainer<TState>,
+): <TSubset>(selector: (state: TState) => TSubset) => TSubset {
+  return selector => {
+    const state = container.getState();
+    return selector(state);
+  };
+}
+
+function makeRequester<TState>(container: StateContainer<TState>) {
+  return <TArgs extends any[]>(
+    requester: (state: RequesterState<TState>, ...args: TArgs) => Promise<void>,
+    ...args: TArgs
+  ): Promise<void> => {
+    const reduce = makeReduce<TState>(container);
+    const select = makeSelect<TState>(container);
+    return requester({ reduce, select }, ...args);
+  };
+}
+
 function initializeObject<TState>(
   container: StateContainer<TState>,
 ): StateContainerType<TState> {
-  const obj: Partial<StateContainerType<TState>> = {};
+  const obj: Partial<StateContainerType<TState>> = {
+    subscribe: container.subscribe.bind(container),
+    unsubscribe: container.unsubscribe.bind(container),
+    reduce: makeReduce(container),
+    request: makeRequester(container),
+  };
 
   Object.defineProperty(obj, 'currentState', {
     get: () => container.getState(),
   });
-  obj.subscribe = container.subscribe.bind(container);
-  obj.unsubscribe = container.unsubscribe.bind(container);
-  obj.reduce = makeReduce(container);
   return obj as StateContainerType<TState>;
 }
 

packages/core/src/types.ts

@@ -22,12 +22,24 @@ export type TransformersTree<TTransformers extends {}> = {
     : TTransformers[TKey]
 };
 
+export type RequesterState<TState> = {
+  select<TSubset>(selector: (state: TState) => TSubset): TSubset;
+  reduce<TArgs extends any[]>(
+    reducer: (state: TState, ...args: TArgs) => TState,
+    ...args: TArgs
+  ): TState;
+};
+
 export type StateContainerType<TState> = {
   currentState: TState;
   reduce<TArgs extends any[]>(
     reducer: (state: TState, ...args: TArgs) => TState,
     ...args: TArgs
   ): TState;
+  request<TArgs extends any[]>(
+    requester: (state: RequesterState<TState>, ...args: TArgs) => Promise<void>,
+    ...args: TArgs
+  ): Promise<void>;
   subscribe(fn: Subscription): void;
   unsubscribe(fn: Subscription): void;
 };